Sample Notes 



All of the samples in this sample set, except the one collected from Nelson Creek, were 

 septic, black in color, and smelled of rotten eggs (H2S). Decomposition of soft algae was not 

 complete, however, allowing for identification of most specimens. Diatoms and blue-green 

 algae (cyanobacteria) were more resistant to decay than green algae, which were the most 

 problematic to identify. Most of the samples were silty to extremely silty, except for upper 

 Horse Creek, Nelson Creek, and Redwater River at the Fairgrounds. Fine particulate organic 

 matter (FPOM) was abundant in samples collected from the lower 3 Redwater River sites and 

 from upper Sand Creek. The samples from upper Horse Creek, Nelson Creek, and Redwater 

 River at Fairgrounds contained moss and/or macrophytes. 



Non-Diatom Algae (Table 3) 



McCone County streams supported 18 genera of non-diatom algae in 4 algal divisions 

 (Table 3). Green algae and cyanobacteria were the most diverse and most abundant groups of 

 non-diatom algae. Each site supported from 2 to 9 genera of non-diatom algae. 



Diatoms accounted for most of the biovolume in these samples except for the 3 Horse 

 Creek sites and the lower site on Redwater River (Table 3). Filamentous cyanobacteria 

 {Lyngbya and Oscillatoria) dominated at the upper 2 Horse Creek sites and the filamentous green 

 alga Rhizodonium was the most abundant alga in samples from lower Horse Creek and the lower 

 site on Redwater River. Rhizodonium has been reported to cause problems in standing and 

 slowly flowing waters across the western United States (Wehr and Sheath 2003). Algae interfere 

 with water uses — e.g., fishing, swimming, boating, and irrigation — only when standing crops are 

 excessive. Mat-forming filamentous algae are normal components of many aquatic ecosystems, 

 including prairie streams, and there is no evidence from this study that standing crops of 

 Rhizodonium are excessive in these streams. Also, criteria have not been established for 

 determining when algal growth in prairie streams is excessive. 



